The Sharkfighters (1956)

Landing on a small island not far from Havana, Cuba, Lt. Cmdr. Ben Staves joins a Navy scientific project engaged in finding an effective shark repellent to help save the lives of WWII military personnel stranded in shark-infested waters. His zeal for completing the project as fast as possible is explained by his having lost a large percentage of his crew to sharks when his ship was sunk by the Japanese. Against the advice of the others on the project, Staves demands that the new repellent be tested on a live subject surrounded by hungry sharks and will allow no one but himself to be the test subject!